TY - JOUR

T1 - Geometric phase in entangled systems

T2 - A single-neutron interferometer experiment

AU - Sponar, S.

AU - Klepp, J.

AU - Loidl, R.

AU - Filipp, S.

AU - Durstberger-Rennhofer, K.

AU - Bertlmann, R. A.

AU - Badurek, G.

AU - Rauch, H.

AU - Hasegawa, Y.

PY - 2010/4/30

Y1 - 2010/4/30

N2 - The influence of the geometric phase on a Bell measurement, as proposed by Bertlmann [Phys. Rev. A 69, 032112 (2004)] and expressed by the Clauser-Horne-Shimony-Holt (CHSH) inequality, has been observed for a spin-path-entangled neutron state in an interferometric setup. It is experimentally demonstrated that the effect of geometric phase can be balanced by a change in Bell angles. The geometric phase is acquired during a time-dependent interaction with a radiofrequency field. Two schemes, polar and azimuthal adjustment of the Bell angles, are realized and analyzed in detail. The former scheme yields a sinusoidal oscillation of the correlation function S, dependent on the geometric phase, such that it varies in the range between 2 and 2√2 and therefore always exceeds the boundary value 2 between quantum mechanic and noncontextual theories. The latter scheme results in a constant, maximal violation of the Bell-like CHSH inequality, where S remains 2√2 for all settings of the geometric phase.

AB - The influence of the geometric phase on a Bell measurement, as proposed by Bertlmann [Phys. Rev. A 69, 032112 (2004)] and expressed by the Clauser-Horne-Shimony-Holt (CHSH) inequality, has been observed for a spin-path-entangled neutron state in an interferometric setup. It is experimentally demonstrated that the effect of geometric phase can be balanced by a change in Bell angles. The geometric phase is acquired during a time-dependent interaction with a radiofrequency field. Two schemes, polar and azimuthal adjustment of the Bell angles, are realized and analyzed in detail. The former scheme yields a sinusoidal oscillation of the correlation function S, dependent on the geometric phase, such that it varies in the range between 2 and 2√2 and therefore always exceeds the boundary value 2 between quantum mechanic and noncontextual theories. The latter scheme results in a constant, maximal violation of the Bell-like CHSH inequality, where S remains 2√2 for all settings of the geometric phase.

UR - http://www.scopus.com/inward/record.url?scp=77951713047&partnerID=8YFLogxK

U2 - 10.1103/PhysRevA.81.042113

DO - 10.1103/PhysRevA.81.042113

M3 - Article

AN - SCOPUS:77951713047

SN - 1050-2947

VL - 81

JO - Physical Review A

JF - Physical Review A

IS - 4

M1 - 042113

ER -